Harald Conrad Stilling was a Danish architect who was active in Copenhagen during the Late Classical period of the mid-18th century. He received the C. F. Hansen Medal in 1841.
Stilling was born in Hørsholm. His father Conrad Frederik Stilling (1766 – 1821) was cup-bearer for Prince Christian Frederik and his mother Juliane Sofie née Hinzpeter (1777 – 1849) was the daughter of the steward at Hirschholm Palace. He spent his first childhood years in his maternal grandfather's home and was then sent to school in Copenhagen before completing a mason's apprenticeship in 1933. He spent the next few years working as a mason in the summer time and studying under Gustav Friedrich Hetsch both privately and at the Royal Danish Academy of Fine Art. He won the Academy's small silver in 1839, its large silver medal in 1840, its small gold medal for the design of a country house in 1843 and its large gold medal for the design of an arsenal in 1847. He worked as an assistant for G.F. Hetsch in 1836–42.
Stilling's first independent works were for Georg Carstensen in Tivoli Gardens. For Carstensen he later also designed the now demolished Casino Theatre in Amaliegade. Another prominent client was I. C. Jacobsen for whom he designed several buildings at his new Carlsberg brewery.
Stilling served as building inspector in Copenhagen in 1856–71 and city architect (stadsbygmester) from 1872–87.